1. Field of the Invention
The Invention in general relates to security systems and in particular a wireless security system having one or more detector/sending units for reporting the existence of a condition to a central receiving unit.
2. Description of the Prior Art
Security systems which include one or more sending units which transmit coded radio frequency (r-f) signals to a central receiving unit which decodes the signals to produce an alarm or other indication of a condition at the sending unit location are well known. The condition may be the existence of a fire, an intrusion, an emergency, the presence of water or other fluid, or other condition desired to be monitored. Or the condition may be the status of the sending unit, such as the condition of its battery or other sensor status. Generally, the information sent will also include the identity or location of the sending unit. The term "security system" as used herein is intended to include any such system that sounds an alarm or reports on one or more conditions.
A problem with r-f or wireless security systems is that electrical interference may disturb or disrupt the transmission of data. Such disruption or disturbance is often referred to as "jamming". Insofar as known to me, no prior art security system includes a means for detecting jamming. Since jamming may be intentional, in order to subvert the system, and even when it is not intentional it may indicate a serious problem with the system, it would be highly desirable to have a means for detecting jamming in a security system. Moreover, in the prior art systems interference often causes false alarms, which have been a hindrance to the acceptance of security systems by the public. Thus a security system that can detect interference and disregard false alarms while the interference is occurring would be a significant advance in the art of security systems.